# HEP/Astro Seminar -- Wednesday, 14 February 2001

##
Hadronic structure of the photon in lattice QCD

## Abstract

We show that the matrix element of a local quark-gluon operator
in the photon state,
⟨γ(*k*λ)|*Ô*|γ(*k*λ)⟩
can be calculated in lattice QCD when there exists a energy gap
between the photon and the hadronic states. The result is generalized
to other quantities involving space-like photons
such as the transition form factor
γγ^{*}→π^{0}
and the virtual-photon-nucleon Compton amplitude
⟨γ^{*}*N* |γ^{*}*N*⟩.
Using this result, the first moment of the photon structure function,
⟨*x*⟩^{γ}=∫_{0}^{1}*dx F*_{2}^{γ}(*x,Q*^{2})
on β=6.0 quenched lattices is measured
and compared with theoretical predictions and the experimental results.

## References

*"Studying hadronic structure of the photon in lattice QCD,"*
Xiangdong Ji and Chulwoo Jung,
Phys. Rev. Lett. **86**, 208 (2001)
, hep-lat/0101014.

## 3:30pm, Smith Lab 1094

George T. Fleming
(
gfleming@mps.ohio-state.edu
),
last updated 24 January 2001.